Gil Kalai’s blog

Noise

What is the correct picture of our world? Are noise and errors part of the essence of matters, and the beautiful perfect patterns we see around us, as well as the notions of information and computation, are just derived concepts in a noisy world? Or do noise and errors just express our imperfect perception of otherwise perfect laws of nature? Talking about an inherently noisy reality may well reflect a better understanding across various scales and areas.

“Are noise and errors part of the essence of matters, and the beautiful perfect patterns we see around us, as well as the notions of information and computation, are just derived concepts in a noisy world? Or do noise and errors just express our imperfect perception of otherwise perfect laws of nature?”

Dear Michael, fualt-tolerance quantum computation is based on a remarkable theorem called the “threshold theorem” which was proved by several groups of researchers in the mid 90s. Since then there have been significant progress in extending the scope of the theorem in terms of the type of noise it can handle, and reducing the numerical value of the threshold.

A breakthrough work by Knill uses error-detection codes rather than error-correction codes and massive post-selection. This allows one to raise the value of the threshold (based on numerical simulations) to 0.03 or so. This idea also leads to a substantially higher provable bounds and there are several papers, including I believe the one you cited, that demonstrate it. This is an exciting direction.